The influence of occupational exposures on male reproductive function

Occupational Medicine 2006; 56: 544-553.
Jensen Tina Kold, Bonde Jens Peter and Joffe Michael

Many studies have found a decrease in semen quality which has increase the focus on male reproductive health.

Welding and Metals

New evidence suggest that metal welding is not as damaging to male reproduction as previously suggested, probably because the exposure levels in the Western world has decreased.
Some specialized workers may however still perform tasks (e.g. stainless steel welding) which may damage their reproduction.

Rachootin et al. / Mortensen / Bonde / Jelnes et al. / Ernst / Ernst et al. / Bonde et al. / Bonde / Bonde et al. / Hjollund et al. / Hjollund et al. / Hjollund et al. / Bonde / Hjollund et al. / Hjollund et al.

Inorganic lead

The male reproductive toxicity of lead has been known for a long time.

There is evidence of an adverse effect of inorganic lead on male reproduction and fecundity.

Other metals

Several studies in rats and mice have demonstrated testicular toxicity of a number of other metals including cadmium, mercury, boron, manganese, and hexavalent chromium but human data are sparse.

Alexander et al. / Wildt et al. / Assennato et al. / Lancranjan et al. / Viskum et al. / Robbins et al. / Bonde et al. / Apostoli et al. / Joffe et al. / Shiau et al. / Benoff et al. / Bonde / Hubbard

Physical exposures

Heat and sedentary body posture

It is well known that internal heating (fever) and external heating for short period of time may result in a dramatic but temporary decrease of sperm count and other aspects of semen quality after a delay of some 6-8 weeks.

Studies among bakers, ceramics workers, foundry workers have indicated reduced sperm counts (Review by Thonneau et al., 1998).

Semen characteristics in specialized welders declined significantly (Bonde, 1993)

Sedentary work position is associated with an increased scrotal temperature.
Taxi drivers in Rome: decreased number of morphological normal sperms (Figa-Talamanca et al., 1996).
Effect of sedentary work needs to be further explored.

Radiation

Testicular tissue is highly sensitive to ionizing radiation.
0.15 Gy may temporarily reduce sperm counts, 2 Gy may result in longlasting or permanent azoospermia.

Rowley et al., 1974

An occupational exposure limit of 15 mSv/year has been adopted in several countries.

Chemical exposures

Solvents

Availabe data suggest that a number of solvents used in industries can affect male reproductive function (glycol ethers (2-EE, 2-ME), 2-bromopropane, carbon disulphide), while the evidence for others is more limited.

Welch et al. / Figa-Talamanca et al. / Veulemans et al. / Lancranjan et al/ Lancranjan et al. / Cirla et al. / Meyer / Wagar et al. / Vanhoorne et al. / Vanhoorne et al. / Jelnes / Kolstad et al. / Eskenazi et al. / Eskenazi et al/ Tola et al. /Rasmussen et al. /Chia et al. / Kim et al. / Liu et al.

Pesticides

A few studies indicate that persistant organochlorine pollutants interfere with sperm motility and sperm DNA integrity

Goldsmith et al. / Potashnik et al. / Sandifer et al. / Ratcliffe et al. / Wong et al. / Zober et al. / Whorton et al. / Wyrobek et al. / Taylor / Taylor / Guzelian / Cannon et al. / Swan et al. / de Cock et al. / Abell et al. / Abell et al. / Abell et al. / Jensen et al. / Larsen et al. / Larsen et al. / Spano et al. / Toft et al.

Psychological exposures

Occupational stress and burn-out have been related to male infertility and reduced semen quality (Sheiner et al., 2002 & Clarke et al., 1999).

Effect of psychological stress on semen quality and male reproductive health is currently not determined.

Hjollund et al., 2004 (job strain)
Hjollund et al., 2004 (male psychologic stress)

Conclusions and recommendations:

Several occupational and environmental exposures and toxins have known or suspected deleterious actions to male reproductive function.

The evidence is strongly supported in well-designed epidemiological studies for heat, ionizing radiation, inorganic lead, DBCP, EDB, some ethylene glycol ethers, carbon disulfide and welding operations.

For other agents the association is only suspected or suggested and needs further evaluation before conclusions can be drawn.